1. Field of the Invention
The present invention relates to a plastic tank for liquids, which is formed as a rectangular-solid or cubic tank with four sidewalls, an upper base with a closable filling socket, a lower base, and an outlet socket, which is formed on the lower section of a sidewall for connection to a tapping valve.
2. Description of the Related Art
During the shipment of liquids in liquid tanks of this general type, which are described in DE 103 01 517 B3 and used as inner tanks of pallet tanks, the sidewalls and the upper and lower bases of the tank are subject to variable internal pressure stresses due to “sloshing” of the liquid in the inner tank, which is caused by the startup, acceleration, and braking of the transport vehicle and by driving vibrations transmitted by the chassis. The four upper corner regions, in which the rounded vertical edge between two adjacent sidewalls and the two rounded horizontal edges between the upper base and the adjacent sidewalls meet, are especially subject to high stresses, since the internal pressure forces acting on the sidewalls are superimposed on those acting on the upper base in these corner regions. Due to the variable internal pressure stress and the oscillatory motion that it produces in the sidewalls and upper base of the tank, the danger exists, especially in the upper corner regions of the plastic tank, that cracks will develop, through which liquid can leak from the tank, so that safe shipment of the liquid tank is no longer guaranteed.